Which is more intelligent: a dog or a mosquito? You will not think twice to answer the question. Bigger animals tend to be smarter and more intelligent. However, does their skeletal system have anything to do with their intelligence?
It is not wise to generalize about smartness and intelligence when it comes to invertebrates. They are diverse in size and form. There are hardly any similarities among species as different as enormous moths, ethereal medusas, skittering scorpions, or stationary sponges. However, there is no need for any debate on this: the lack of a backbone may mean they are ‘spineless’, however, that does not mean that all of them are mindless!
Cephalopods, squid and octopus in particular, are some of the most intelligent invertebrates. They are capable of learning quickly and retaining information. Spiders learn to weave better webs through trial and error. Honeybees learn to recognize their hives. At the same time, curiously enough, starfish and sponges do very well with no brains at all!
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